Numerous studies have demostrated that patients with affective disorders have cholinergic supersensitivity. The neuroendocrine challenge test to measure it employs pyridostigmine, which increase cholinergic tone in the hypothalamus, thereby releasing GH. This is a single study indicating that the patients who were probably bipolar and had brief improvement in their thought disorders after a trial with physostigmine, went on to be lithium responders. We wish to test the hypothesis that patients with affective disorders have cholinergic supersensitivity and determine if this supposed supersensitivity is a marker of response as well as certain personality traits, psychosensory experience, and the results of the challenge test. To date 10 patients have been enrolled (3 controls and bipolar). The investigators would like to make changes to this study. In order to allow for a greater variety of patients to enter the protocol. The investigators are proposing an amendment to the protocol that they hope will allow for improved recruitment of subjects. Although the investigators wish to change the protocol by broadening the inclusion criteria, the actual challenge test itself will be performed as per the original protocol. Amendment Criteria: 1. The investigators propose that the unipolar and panic disorder patietns only receive one challenge test per protocol on Day 1. By doing so, patients who are to entger monotherapy randomized clinical trials, where rechallenging of treated pateitns would not be possible as the investigators would not know whether a patient is on active agent or placebo, can have this study "piggy-backed" on where allowed. 2. The investigators propose that 16-30 additional bipolar patients who are to receive monotherapy treatment other than lithium be entered. These bipolar patietns will not be rechallenged, but will be monitored for four weeks after the challenge test. 3. These patients will have the same screening as in the original protocol and will progress though the rating scales portion of the original protocol. Patients will be entered, as per the original protocol, who are not on any psychotropic medications other than benzodiazepines. Thus, the central difference from the original protocol is that unipolar, panic and additional bipolar patients will not be rechallenged at 4 weeks and that bipolar patients in this additional group will be treated with other mood stabilizers (such ad Depakote).